1. Technical Field
This invention relates to eyeglass frame hinges. The invention also relates to frames that provide their wearers with multiple wearing choices/options, i.e. both in and outside of a safety mask, with or without added safety shields and with side temple arms, head straps or both. More specifically, the invention relates to improved spectacle kits for protective masks.
2. Background
Firemen, safety and rescue personnel, and industrial professionals often require protective masks or Self Contained Breathing Apparatus (SCBA). Such masks are needed when entering a hazardous environment such as a burning structure or an area known or suspected of containing a caustic, chemical gas. Some sports also require protective masks like those used in underwater diving.
A person requiring corrective optical lenses must be able to use his/her lenses while wearing a protective mask. The use of contact lenses while wearing a mask is impractical because most contacts today are soft lenses manufactured from materials containing 38% by weight or more water. Such soft lenses are easily contaminated by smoke and/or chemicals making them uncomfortable to wear or structurally damaging same.
A typical spectacle kit includes framed optical lens structures supported on the nose or face, more commonly called eyeglasses. Many of today's kits use thermo plastic lenses, e.g., CR39 monomer polycarbonate lenses, to provide vision correction to a given prescription.
Spectacle kits are needed for those who have to wear protective masks while requiring corrective optical lenses. One method used in the past, including by the military, connects lens frames by a hinged nosepiece for holding the eyeglasses in the mask proper. A second method attaches a support structure to a back block rigidly mounted inside a facemask. Those lens frames can be removed by pulling the whole unit out of the mask.